Electro-hydraulic blowout preventer



May 16, 1967 J. A. HAEBER ETAL 7 Sheets-Sheet 1 INVENTORSZ J. A. HAEBERK. W. FOSTER HEIR AGEN J. A. HAEBER ETAL ELEGTRO-HYDRAULIC BLOWOUTPHEVENTER 7 Sheets-Sheet 2 Original Filed April 20, 1962 INVENTORS J AHAE BER K. W FOSTER l-FM THEIR AGEN May 16, 1967 J. A. HAEBER ETALELECTRO-HYDRAULIC BLOWOUT PREVENTER 7 Sheets-Sheet 5 Original FiledApril 20, 1962 INVENTORSI J. A. HAEBER K. W. FOSTER W 44.10%

THEIR AGEN y 1967 J. A. HAEBER ETAL 3,319,923

ELECTRO-HYDRAULIC BLOWOUT PREVENTER Original Filed April 20, 1962 '7Sheets-Sheet 4 1 f IE2] y '7 I HT L I "14. IN I! 2 l r 5 m i l i 1 2 I m3 i m v I I 2 i I l u.

VV :7 i I r I H 8 I 1 l I I I a a I IO I g m I I 2 INVENTORSI THEIRAGENT May 16, 1967 J. A. HAEBER ETAL 3,319,923

ELECTRO-HYDRAULIC BLOWOUT PREVENTER Original Filed April 20, 1962 I 7Sheets-Sheet 5 FIG. 5

INVENTORSI J. A. HAEBER K. W. FOSTER THEIR AGE May 16, 1967 J. A. HAEBERETAL ELECTROHYDRAUL|IC BLOWOUT PREVENTER 7 Sheets-Sheet 6 Original FiledAnril 20, 1962 INVENTORSI a. A. HAEBER K. w. FOSTER 8Y1, Him

THEIR AGE May 16, 1967 J. A. HAEBER ETAL 3,319,923

ELECTROHYDRAULIC BLOWOUT PREVENTER Original Filed April 20, 1962 '7Sheets-Sheet 7 POWER SUPPLY ADJUSTABLE CURRENT CURRENT SENSITIVE RELAYI30 REVERSING POWER SWITCH SUPPLY |27"""\ I j VARIABLE VOLTAGE MMCONTROLLER l l 97 v I25 I28 (I24 MAGNETIC CIRCUIT 96 CONTACTOR BREAKEREII 2 RELAY FIG. I0

I00 8O m it; 52g 60 FIG.H

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APPLIED VOLTAGE INVENTORS J.A. HAEBER K. W. FOSTER THEIR AGE UnitedStates Patent Ofiice 3,319,923 Patented May 16, 1967 3,319,923ELECTRO-HYDRAULIC BLOWOUT PREVENTER John A. Haeber and Kenneth W.Foster, Houston, Tex.,

assignors to Shell Oil Company, New York, N.Y., a corporation ofDelaware Original application Apr. 20, 1962, Ser. No. 189,113, nowPatent No. 3,250,336, dated May 10, 1966. Divided and this applicationJuly 16, 1965, Ser. No. 482,970 3 Claims. (Ci. 2511) The presentapplication is a divisional application of copending application Ser.No. 189,113, filed Apr. 20, 1962 and now Patent No. 3,250,336.

This invention relates to a blowout preventer adapted to be secured to awell casinghead to control the pressure therein. The invention pertainsmore particularly to a blowout preventer for use in drilling, completingand work-over operations in oil and gas wells at offshore locationswherein the wellhead assembly is positioned at a substantial depth belowthe surface of a body of water and operations are carried on from afloating platform on the surface of the water. If desired, a blowoutpreventer in accordance with the present invention may be left on awellhead assembly while the well is in production.

During various stages of drilling, production or servicing of an oilwell, there are occasions when the pressure in the well is sufficient toforce the contents of the well upwardly out of the well, whether thecontents of the well be oil, drilling mud, completion fluid, or thelike. A blowout preventer is therefore provided at the top of the wellfor sealing off the Well during such intervals. It may be necessary toclose one or more blowout preventers and seal off the well while a drillpipe is in the well, while a tubing string is passing through thecasinghead, or while the well and/or casinghead are otherwise empty.

A blowout preventer of the ram type comprises a hollow body memberhaving aligned pipe openings in one pair of opposite walls to provide apipe passage therethrough, and a pair of horizontally slidable ramsarranged for movement toward and away from the pipe passage in thepreventer body so as to seal the pipe passage when the rams are in theclosed position. Each ram carries a resilient sealing member or valvehead arrangd to engage its cooperating ram in a fluidtight manner. Oneset of rams when closed together has a hole extending therethrough whichis of slightly smaller diameter than the diameter of a drill pipeagainst which it is adapted to seal in a fiuidtight manner. The otherpair of rams in the blowout preventer, known as blind rams, havestraightedged resilient sealing members adapted to seal against eachother when there is no pipe or tubing string extending through theblowout preventer.

The rams in one type of blowout preventer are closed manually by anoperator turning hand wheels connected to threaded valve stems which inturn are connected to the rams. Thus, the blowout preventer is closed inthe same manner that two valves would be closed that are set at 180 toeach other to close one against the other. It is obvious thatmanually-actuated valves could not be used in drilling underwater wells.Hence, it is a primary object of the present invention to provide ablowout preventer which may be opened or closed remotely, as from adrilling platform or vessel positioned on the surface of the water, orfrom a remote location in land operations.

Blowout preventers with hydraulically-actuated rams have been used inwell drilling operations on land and are presently the most common typeused. The use of hydraulically-operated blowout preventers for drillingunderwater wells has not proved entirely satisfactory due to the factthat the hydraulic pressure lines may be easily ruptured and thepressure drop in the hydraulic lines due to friction loss reduces theamount of available pressure to be supplied to the rams of the blowoutpreventer. The pressure drop in the hydraulic lines may be ovecome onlyby using very large diameter hydraulic lines, but these ar very heavyand cumbersome to handle in offshore operations where the drillingplatform or vessel may be several hundred feet above the wellheadpositioned on the ocean floor.

It is therefore another object of the present invention to provide anelectrically-operated blowout preventer which may be operated by asingle multi-conductor electric transmission line extending from adrilling platform above the surface of a body of water to the blowoutpreventer and wellhead apparatus positioned near the ocean floor.

As an emergency control feature, it is a further object of the presentinvention to provide an electrically-operated blowout preventer, forland or sea operations, with a hydraulic prime mover which is adapted toover-ride a nonoperative electrical prime mover that is normallyemployed to operate the blowout preventer.

Another object of the present invention is to provide anelectrically-operated blowout preventer wherein the closing force of therams of the preventer may be adjustably controlled from a remotelocation, as from a drilling platform on the surface of the water.

These and other objects of this invention will be understood from thefollowing description taken with reference to the drawing, wherein:

FIGURE 1 is a diagrammatic view taken in longitudinal projectionillustrating a floating drilling barge positioned on the surface of theocean with an underwater Wellhead assembly positioned on the ocean floorwhen well drilling operations are being carried out;

FIGURE 2 is a fragmental view of the ram type blowout preventer ofFIGURE 1 taken partly in cross section and partly in phantom showing thesealing face of the upper far ram and the back end of the lower nearram;

FIGURE 3 is a cross-sectional view taken along the line 3-3 of FIGURE 2showing a segment of pipe positioned between the upper rams of theblowout preventer;

FIGURE 4 is a view taken partially in cross section of an electricoperator adapted with secondary hydraulic over-ride apparatus of theblowout preventer of FIG- URE 1;

FIGURE 5 is a view taken in the line 55 of FIGURE 4;

FIGURES 6, 7, 8 and 9 are isometric views diagrammatically illustratingvarious arrangements whereby the electric operators with secondaryhydraulic over-ride apparatus of the present blowout preventer may beconnected to actuate one set of rams thereof;

FIGURE 10 is a diagrammatic view illustrating one type of controlcircuit for the blowout preventer of the present invention; and,

FIGURE 11 illustrates a typical curve which may be obtained whenplotting ram thrust against applied voltage for one form of a blowoutpreventer.

Referring to FIGURE 1 of the drawing, a drilling platform or barge -11of any suitable floatable type is illustrated as floating on the surfaceof a body of water 12 and being substantially fixedly positioned over apreselected drilling location by suit-able barge-positioning means or bybeing anchored to the ocean floor 13 by suitable anchors (not shown)connected to the anchor lines 14 and 15. Equipment of this type may beused when carrying on well drilling operations in water depths varyingfrom about to 1500 feet or more. The drilling barge is equipped with asuitable derrick 16 as well as other auxiliary equipment needed duringthe drilling of a well or during work-over operations. The derrick 16 ispositioned over a drilling slot or well 18 which extends verticallythrough the barge in a conventional manpartial cross section along ner.When using the equipment of the present invention, the slot of the barge11 may be either centrally located or extend in from one edge. However,drilling operations may 'be carried out over the side of the barge orplatform without the use of a slot. Additionally, it is to be understoodthat the equipment of the present invention may also be used whendrilling a well from any suitable operational base positioned above thesurface of the water, such for example, as from a platform permanentlypositioned on the ocean floor.

A typical underwater wellhead structure or assembly is illustrated inFIGURE 1 as comprising a base member 21 which is positioned on the oceanfloor 13 and is fixedly secured to a conductor pipe or a large-diameterwell casing 22 which extends down into a well, which has been previouslydrilled, and is preferably cemented or otherwise anchored therein. Thus,the base structure 21 is rigidly secured to the ocean floor in order tosupport two or more vertically-extending guide columns 23 and 24 adaptedto receive and guide therein guide arms 25 and 26, 25a and 26a and 25band 26b, which are arranged to slide on vertically-extending guidecables 27 and 28. The lower ends of the guide cables 27 and 28 areanchored to the base structure 21 within the guide columns 23 and24'while extending upwardly through the water to the drilling barge 11where they are preferably secured to constant tension hoists 31 and 32.It is to be understood that in an emergency a single guide arm on aguide cable extending between the bases structure 21 and the drillingvessel 11 may be employed to position a piece of equipment on thewellhead. A two-cable guide system will be described hereinbelowalthough generally a guide system having at least three guide cables ispreferred.

Centrally positioned above the base member 21 and fixedly securedthereto, or to the conductor pipe 22, is a well casinghead unit 33 whichmay be provided with a cement circulation or fluid return line 36 whichmay be selectively closed by a remotely-operated valve (not shown). Theguide arms 25 and 26 are illustrated as being connected to a wellheadconnector unit 40 which may be hydraulically or electrically actuated toconnect to the top of the casinghead 33 in a manner described incopending patent application, Ser. No. 105,068, filed Apr. 24, 1961 andnow Patent No. 3,163,222. In the above-identified patent application awellhead connector 40 is provided with a self-containedelectro-hydraulic operating unit which is provided with operating powerby an electrical transmission line running from the barge 11 to theunderwater wellhead assembly. Alternatively, the wellhead connectorcould 'be hydraulically operated by means of a pressure fluid linerunning to the barge 11.

During the drilling, completion and working over of a well, one or moreblowout preventers are normally connected coaxially above the wellheadconnector 40. In FIGURE 1 a series of four blowout preventers 43, 44, 45and 45a are illustrated as being fixedly secured together and forming aunitary package with the wellhead connector 40, which package is adaptedto be lowered onto the casinghead 33 in any suitable manner. The lowerblowout preventers 43 and 44 are of the ram type and may be mounted in acommon housing as will be described hereinbelow. Likewise, the upperblowout preventers which are preferably of the radially-contractible"cartridge type packing unit design, are mounted in a common housing,each packer of blowout preventers 45 and 45a being actuated by aself-contained electro-hydraulic operating unit 46 and 47, respectively.The selfcontained electro-hydraulic operating units 46 and 47 aredescribed in copending patent application, Ser. No. 105,068, filed Apr.24, 1961, are connected by means of hydraulic conduits 48a, 48b, 49a and49b to the interior of the blowout preventers 45 and 45a, while beingsupplied by electric power through transmission cables 50 and 51,respectively. Similar self-contained electro-hydraulic operating unitsmay be mounted on the present drilling assembly of FIGURE 1 forsupplying pressure fluid to the conduits 52 of the wellhead connector 40while other operating units (not shown) could be employed to seal and/or look the landing head 53 to the uppermost blowout preventer 45a, andto operating valves 57 and 58.

Preferably the combined blowout preventers 43, 44, 45 and 45a and thewellhead connector 40 are run together into position on top of the wellby being lowered through the water from the drilling platform 11 bymeans of a pipe string (not shown), commonly known as a running string,with the lower end of the running string being connected to theuppermost blowout preventer 45 by any suitable coupling or connectorwhich may be similar in form to the wellhead connector 40, such as thelanding head 53. After the blowout preventers are installed the runningstring is replaced by a larger diameter pipe string known as a marineconductor pipe which is represented generally in FIGURE 1 by numeral 54.

While the various wellhead components, such for example as the wellheadconnector 40 and the blowout preventers 43, 44, 45 and 45a may behydraulically, pneumatically or electrically actuatable, they arepreferably hydraulically actuatable by means of electrohydraulicoperator units similar to units 46 and 47 although they may be actuatedby means of pressure hoses (not shown) which would extend up through thewater to the drilling barge 11.

The drilling assembly or stack of blowout preventers 43, 44, 45 and 45aon the top of the wellhead connector is provided with one or preferablytwo small-diameter conduits which will be termed hereinbelow as chokeand kill lines 55 and 56, respectively. The choke and kill lines 55 and56 are employed to provide means for establishing fluid communicationbetween the drilling platform 11 and the well during drilling operationsafter one or more of the blowout preventers 43, 44, 45 and/or 45a havebeen closed during an emergency. Thus, the choke line 55 is incommunication at its lower end with the interior of the assembly, andhence the well, below the lowermost blowout preventer 43 while the killline 56 is in communication with the interior of the assembly below theupper set of blowout preventers 45 and 45a. The choke and kill lines 55and 56 are provided with remotely actuatable valves 57 and 58,respectively, which have pressure hoses or electrical transmission lines59 and 60 which extend to the surface or to a valve operator. Sincethese valves and their connection to the releated units do not form anessential part of the present invention and are described in detail inthe above-identified copending patent application, they will not befurther described here.

As shown in FIGURE 1, the lowermost blowout preventers-43 and 44 areprovided wtih operators 63 and 64, respectively, which are primarilyelectrically powered operators for closing the rams of the blowoutpreventers. A typical ram-type blowout preventer housing is shown incross-section in FIGURE 3 as comprising a housing or body member 65having aligned pipe openings 66 and 67 in one pair of opposite walls 68and 69 to provide a passage 70 therethrough for a pipe or tubing member71. An upper pair of pipe rams 72 and 73 (FIGURE 3) forms the upperram-type blowout preventer 44 (FIG- URE l). The rams 72 and 73 areslidably mounted in guideways 74 and 75, respectively, and are actuatedby linkage arms 76 and 77 which are fixedly secured tolaterally-extending shafts 78 and 79. The adjacent portions of the rams72 and 73 are provided with sealing elements 80 and 81. When the sealingelements 80 and 81 of the rams 72 and 73 are in sealing engagement, theytouch each other on both sides and provide a vertical pipe passagethrough the sealing elements having a diameter the same as the outsidediameter of the pipe 71 against which they would seal.

In a like manner the lower ram-type blowout preventer (FIGURE 1)comprises a pair of laterally-movable rams 82 and 83 mounted in ramguideways 84 and 85, respectively, and movable therein by means oflinkage arms 86 and 87 which are fixedly secured to shafts 88 and 89.The lowermost rams 82 and 83, being so called blind rams, are providedwith sealing elements 90 and 91 having horizontally straight surfaces 92and 93 which seal against each other along their entire length when therams 82 and 83 are closed, thereby completely closing the pipe passage70 through the blowout preventer body member 65.

A typical operator, similar to operator 64 for blowout preventer 44(FIGURE 1) is shown in FIGURES 4 and 5. The electrical operatorcomprises a housing 95 (FIG- URE 4) having an electric motor 96 mountedtherein with an electrical transmission line 97 extending through thewall of the housing 95 in a fluidtight manner and thence extending upalong the drilling assembly to the drilling platform 11 at the surface.The motor 96 is preferably a three-phase motor having its shaft 98connected by means of a coupling 99 to a drive shaft 100 which has aworm 101 formed thereon. The drive shaft 100 is rotatably mounted inbearings 102 and 103.

The worm 101 meshes with and is arranged to drive a Worm gear 104 whichis splined to a transverse shaft 105 arranged normal to the drive shaft100. As shown in FIGURE 5 the transverse drive shaft 105 is mounted inbearings 106, 107, 108 and 109 and has formed thereon worms 110 and 111of reverse pitch. Worm 110 engages and is adapted to drive the segmentworm gear 112 in a clockwise direction at the same time that the worm111 which engages segment worm gear 113 drives the latter in acounter-clockwise direction. The segment worm gears 112 and 113 would besplined or otherwise fixedly secured for example, say, to the shafts 78and 79 (FIG- URE 3) of the upper rams 80 and 81 so that movement of thesegment worm gears 112 and 113 in first one direction and then the otherwould move the rams toward and then away from the central pipe passage70 (FIG- URE 3).

For emergency service, the electrical operator of the blowout preventerof the present invention is provided with a hydraulic actuator of anysuitable type which is adapted to open and close the rams of the blowoutpreventer when the electric motor 96 of the operator has failed. Thus,as shown in FIGURE 4, a hydraulic motor 115 is also mounted within theoperator housing 95 and is provided with pressure conduits 116 and 117extending therefrom for supplying a pressure fluid to the motor to drivethe motor in one direction or the other. A preferred arrangement is toconnect the shaft 118 of the hydraulic motor by means of a suitablecoupling 119 to the shaft 98 of the electric motor 96. The hydraulicpressure conduits 116 and 117 (FIGURE 4) could extend to a power source(not shown) on the deck of the platform 11 (FIG- URE 1), or to asecondary-control hydraulic manifold (not shown) but preferably extendto an electro-hydraulic operator unit 121 (FIGURE 1) which is similar tothe electro-hydraulic units 46 and 47 and has an electric transmissioncable 122 extending upwardly to a controller 123 on the deck of thebarge 11.

The electric motor 96 (FIGURE 4) housed in the electric operator ispreferably of a three-phase type having an electric transmission cable97 running to the controller 123 which is remotely positioned on thedeck of the barge 11 (FIGURE 1). The controller 123 is provided withsuitable circuits to each of the electric motors positioned on thewellhead assembly at the ocean floor. One suitable control circuit foran electric motor 96 of the blowout preventer operator is shown inFIGURE as including a variable voltage controller 124 which iselectrically connected to the motor 96 through leads 97 and to a powersupply 125 through a reversing switch 125. The reversing switch is ofany suitable commercial type adapted to reverse the current supply intwo of the three leads to the motor 96 so as to run the motor forward orreverse whereby the rams of the blowout preventer may be open or closed.It is desirable to employ a variable voltage controller or variableautotransformer 124 in the circuit so that the closing force of the ramsof the blowout preventer may be selectively varied by varying thevoltage of the current to the motor 96. One suitable type of a variableautotransformer is one known as Adjust-A-Volt manufactured by StandardElectrical Products of Dayton, Ohio.

It is desirable to be able to adjust selectively the closing force ofthe rams 72 and 73 (FIGURE 3) on a pipe 71 between the rams andextending through the blowout preventer. This is often necessary becauseif you close the rams too tightly on the pipe it is impossible tocirculate fluid in small amounts past them to prevent burning up thesealing elements and 81 when it is desired to rotate or reciprocate apipe string in the blowout preventer with the rams closed. On manyoccasions it is desirable to be able to close the rams of a blowoutpreventer and then back them off slightly so as to be able toreciprocate the pipe in the rams. During some operations while drillingand completing wells from a floating drilling barge, it is impossible toavoid reciprocating a pipe string as the boat moves up and down. Ifmaximum thrust was applied to the rams to close them on a pipe stringpassing through the blowout preventer the pipe string may shear off asthe wave forces raised the boat at the surface. Thus, it is desirable toprovide the blowout preventer of the present invention with acompressioncontrolling device for the rams of the system.

The amount of thrust exerted by the rams of the blowout preventer may bevaried by manually adjusting the variable voltage controller 124 of thecircuit. If desired, a current cut-off circuit may be provided in anysuitable form as by a pair of current transformers 127 and 128 which areconnected to a current-sensitive relay 130 having an adjustable setpoint device 131 and being connected to a power supply source 132through a magnetic contactor relay 133 and a circuit breaker 134 in themain power line to the motor 96. A suitable current-sensitive relay 130may be a continuous Ready Meter Relay type as manufactured by AssemblyProducts Inc. of Chesterland, Ohio. A time delay relay is also builtinto the circuit so that the current sensitive relay will ignore inrushcurrent on the starting of the motor 96. With this type of a currentcut-off circuit added to the main voltage controller circuit, when thepredetermined thrust has been exerted by the rams against a pipe in theblowout preventer, the current transformers would sense an increase incurrent and the signal transmitted to the relay 130 would trip themagnetic contactor relay 133 in the power supply line leaving the ramslocked against the pipe with the preselected force. If a greater ramclosing force were desired, the variable voltage controller would thenbe changed to increase the voltage output thereof, see FIG- URE 11.

While one type of a drive mechanism has been described with regard toFIGURES 4 and 5 which connect the electric motor 96 of the operator tothe rams 72 and 73 of FIGURE 3, it is to be understood that many otherarrangements may be employed as illustrated in FIGURES 6 through 9. Forexample, in FIGURE 6, the shaft 98a of the motor 96a has a worm 101aformed thereon which engages a worm gear 135 formed on a transverseshaft which has reverse pitch worms 137 and 138 formed at opposite endsthereof. The worms 137 and 138 engage worm gear segments 112a and 113ato move the rams 72a and 73a toward and away from each other. In FIG-URE 7 individual electric motors 94b and 96b are individually providedto operate the rams 72b and 73b, the shafts of the motor being connectedto the shafts of the ram through speed reducers or gear trains 140 and141.

In FIGURE 8 a single motor 96c is connected through a speed reducer 142to the end of a shaft 143 having reverse pitch worms 144 and 145 formedthereon. The worms 144 and 145 in turn engage segment worm gears 112aand 113c to drive shafts 78c and 790 and thus move the rams 72c and 73ctoward and away from each other depending upon the direction of whichthe motor 960 is driven.

In the arrangement shown in FIGURE 9 individual motors 94d and 96a areagain employed to drive the individual rams 72d and 73d through speedreducers 146 and 147, worms 148 and 149 of reverse pitch and segmentworm gears 112a and 113d, respectively.

Thus, it may be seen that the apparatus of the present inventionprovides a wellhead positioned below the surface of a body of water andbeneath an operating platform positioned above the surface of the waterwith a large-diameter marine conductor pipe extending from the wellheadto the platform and a plurality of blowout preventers secured to thelower end of the marine conductor pipe and mounted on the wellheadassembly. At least one of the blowout preventers is provided withelectricallyor electro-hydraulically actuated operator means mountedadjacent, the blowout preventer with power transmission means extendingfrom the operator to the operating platform on the surface of the water.Where circuit means are provided for controlling the power supplied tothe operator of the blowout preventer, the control circuit preferablyhaving a suitable device for varying the voltage supplied to theoperator. The term linkage means as employed in the appended claims ismeant to include all of the elements needed to connect operatively theramps 72 and 73 to the motor 76. This would include a motor shaft 98,drive shaft 100, worm 101, worm gear 104, worms 110 and 11, worm gears112 and 113, shafts 78 and 79 and linkage arms 76 and 77 in thearrangement described with regard to FIGURES 3, 4 and 5.

We claim as our invention:

1. A blowout preventer comprising (a) a hollow body member havingaligned pipe openings in one pair of opposite walls to provide a pipepassage therethrough,

(b) at least a pair of oppositely-arranged sealing rams movable towardand away from the central axis of said pipe passage,

(c) sealing means carried on the terminal adjacent portions of said rammeans,

((1) actuating linkage means connected to each of said rams,

(e) electrical motor means carried in fixed relation to said body memberand being operatively connected to said actuating linkage means, and

(f) circuit means for said motor means, said circuit means includingvariable voltage means positioned remotely of said motor means forselectively varying the thrust of said rams at least in their closedposition.

2. A blowout preventer comprising (a) a hollow body member havingaligned pipe openings in one pair of opposite walls to provide a pipepassage therethrough and ram guide means extending laterally from saidpipe passage,

(b) at least a pair of oppositely-arranged sealing rams movable in saidguide means toward and away from the central axis of said pipe passage,

(c) sealing means carried on the terminal adjacent portions of said rammeans,

(d) actuating linkage means connected to each of said rams,

(e) electrical motor means carried by said body member and beingoperatively connected to said actuating linkage means,

(f) circuit means for said motor means including variable voltage meanspositioned remotely of said motor means for selectively varying thethrust of said rams at least in their closed position,

(g) hydraulically-operated motor means carried by said body member onthe outside thereof and being operatively connected to said actuatinglinkage means and being in communication with a source of pressure fluidfor actuation independent of said electric motor means.

3. A blowout preventer comprising (a) a hollow body member havingaligned pipe openings in one pair of opposite walls to provide a pipepassage therethrough and ram guide means extending laterally from saidpipe passage,

(b) at least a pair of oppositely-arranged sealing rams movable in saidguide means toward and away from the central axis of said pipe passage,

(c) sealing means carried on the terminal adjacent portions of said rammeans,

(d) actuating linkage means connected to each of said rams (andextending through the wall of said housing in a fiuidtight manner),

(e) electrical motor means carried by said body member on the outsidethereof and being operatively connected to said actuating linkage means,

(f) circuit means for said motor means including variable voltage meanspositioned remotely of said motor means for selectively varying thethrust of said rams at least in their closed position,

(g) hydraulically-operated motor means carried by said body member onthe outside thereof and being operatively connected through saidelectrical motor means to said actuating linkage means saidhydraulically-operated motor means being arranged for actuationindependent of said electric motor means.

References Cited by the Examiner UNITED STATES PATENTS Re. 19,684 8/1935Young 251-1 887,253 5/1908 Jackson 251- 1,529,005 3/ 1925 Beckwith251-135 X 1,875,673 9/1932 Stockstill 251-1 X 1,925,853 9/1933 Standlee277.129 2,320,974 6/ 1943 MacClatchie 251-.1 3,132,662 5/1964 Allen 2511X 3,179,179 4/1965 Kofahl 166-66 FOREIGN PATENTS 501,166 1953 Italy.

WILLIAM F. ODEA, Primary Examiner.

ISADOR WEIL, Examiner.

R. GERARD, Assistant Examiner.

1. A BLOWOUT PREVENTER COMPRISING (A) A HOLLOW BODY MEMBER HAVINGALIGNED PIPE OPENINGS IN ONE PAIR OF OPPOSITE WALLS TO PROVIDE A PIPEPASSAGE THERETHROUGH, (B) AT LEAST A PAIR OF OPPOSITELY-ARRANGED SEALINGRAMS MOVABLE TOWARD AND AWAY FROM THE CENTRAL AXIS OF SAID PIPE PASSAGE,(C) SEALING MEANS CARRIED ON THE TERMINAL ADJACENT PORTIONS OF SAID RAMMEANS, (D) ACTUATING LINKAGE MEANS CONNECTED TO EACH OF SAID RAMS, (E)ELECTRICAL MOTOR MEANS CARRIED IN FIXED RELATION TO SAID BODY MEMBER ANDBEING OPERATIVELY CONNECTED TO SAID ACTUATING LINKAGE MEANS, AND (F)CIRCUIT MEANS FOR SAID MOTOR MEANS, SAID CIRCUIT MEANS INCLUDINGVARIABLE VOLTAGE MEANS POSITIONED REMOTELY OF SAID MOTOR MEANS FORSELECTIVELY VARYING THE THRUST OF SAID RAMS AT LEAST IN THEIR CLOSEDPOSITION.